The present invention relates to a drive hub for at least partially muscle-powered vehicles and in particular two-wheeled vehicles with an axle and with a hub body is provided rotatably around it and with a sprocket carrier for transmitting the driving force to the drive hub.
Different drive hubs for muscle-powered vehicles such as bicycles have become known in the prior art. Bicycles in the field of sports and for professionals tend to be provided with a gear shift device. Other than transmission hubs, chain shifting devices are in particular employed where a sprocket cluster having multiple drive sprockets is provided the sprockets of which can be selectively actuated to change transmission ratios as desired. Chain shifting devices are advantageous since they show high efficiency and ease of maintenance since each of the sprockets and the chain are accessible from the outside.
These days, so-called cassette hubs tend to be employed in which a rotor is received rotatably relative to the hub axle and which is non-round in its outer contour. A sprocket cluster having a non-round inner contour is pushed onto the non-round outer contour such that the sprocket cluster with its different sprockets is non-rotatably received at the rotor. The sprocket cluster consists of a sprocket carrier and the sprockets disposed thereon.
These known drive hubs operate reliably and allow simple and quick exchange of the sprocket clusters since the sprocket carrier with all the sprockets is provided for simple exchange. Since each sprocket is subjected to wear, this enables an effective exchange of individual or all of the sprockets.
The drawback of these known hubs is the high space requirement. The drive hub rotor must have a certain outer diameter for receiving the bearings to support the rotor. This in turn requires a certain minimum diameter and a not inconsiderable weight. The inner hub diameter is specified though since the axle needs to be compatible with the usual standards. For example through axles are 12 mm in diameter.
With DE 10 2009 006 101 A1 a hub arrangement has become known having a hub body, a fixed axle and a conical set of sprockets arranged rotatably relative to the fixed axle. The extreme end of the set of sprockets is provided with a bearing by way of which the set of sprockets is supported on the fixed axle. With its other end the set of sprockets radially surrounds the hub body. To facilitate rotation the exterior of the hub body may be provided with a bushing which serves as a gliding bushing, reducing friction between the set of sprockets and the hub body. Basically this hub arrangement allows the achievement of low weight. The drawback is, however, that the set of sprockets, which must transfer the entire driving energy to the hub body, is supported on one bearing only. The bushing provided at the other end is wholly exposed to environmental influences, forming a potential weak point. Although one might provide instead of the bushing, a roller bearing, it would considerably increase the weight given the large diameter, and it would again have to be protected from dirt and moisture.